<?php
// =======================================================
// Example of how to format US Postal shipping information
// =======================================================
require_once ('jpgraph/jpgraph_barcode.php');

// The Full barcode standard is described in
// http://www.usps.com/cpim/ftp/pubs/pub91/91c4.html#508hdr1
//
// The data start with AI=420 which means
// "Ship to/Deliver To Postal Code (within single authority)
//
class USPS_Confirmation {
	function USPS_Confirmation() {
	}

	// Private utility function
	function _USPS_chkd($aData) {
		$n = strlen($aData);

		// Add all even numbers starting from position 1 from the end
		$et = 0 ;
		for( $i=1; $i <= $n; $i+=2 ) {
			$d = intval(substr($aData,-$i,1));
			$et += $d;
		}

		// Add all odd numbers starting from position 2 from the end
		$ot = 0 ;
		for( $i=2; $i <= $n; $i+=2 ) {
			$d = intval(substr($aData,-$i,1));
			$ot += $d;
		}
		$tot = 3*$et + $ot;
		$chkdigit = (10 - ($tot % 10))%10;;
		return $chkdigit;
	}

	// Get type 1 of confirmation code (with ZIP)
	function GetPICwithZIP($aZIP,$aServiceType,$aDUNS,$aSeqNbr) {
		// Convert to USPS format with AI=420 and extension starting with AI=91
		$data = '420'. $aZIP . '91' . $aServiceType . $aDUNS . $aSeqNbr;
		// Only calculate the checkdigit from the AI=91 and forward
		// and do not include the ~1 (FUNC1) in the calculation
		$cd = $this->_USPS_chkd(substr($data,8));
		$data = '420'. $aZIP . '~191' . $aServiceType . $aDUNS . $aSeqNbr;
		return $data . $cd;
	}

	// Get type 2 of confirmation code (without ZIP)
	function GetPIC($aServiceType,$aDUNS,$aSeqNbr) {
		// Convert to USPS format with AI=91
		$data = '91' . $aServiceType . $aDUNS . $aSeqNbr;
		$cd = $this->_USPS_chkd($data);
		return $data . $cd;
	}

}

$usps = new USPS_Confirmation();
$zip     = '92663';
$service = '21';
$DUNS    = '805213907';
$seqnr   = '04508735';
$data = $usps->GetPICwithZIP($zip,$service,$DUNS,$seqnr);
//$data = $usps->GetPIC('01','123456789','00000001');

$encoder = BarcodeFactory::Create(ENCODING_EAN128);
$e = BackendFactory::Create(BACKEND_IMAGE,$encoder);
$e->SetModuleWidth(2);
$e->SetFont(FF_ARIAL,FS_NORMAL,14);
$e->Stroke($data);

?>